yodack: Minor coding style touch-up

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>
yodack: Allow the test suite to run on non-english locales

Set the locale to C before running GnuPG in the test suite, so that we
can grep for an english string in its output.

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>